Motorized wheelchairs are becoming, increasingly popular for people with ambulatory difficulties. Typically, these chairs include a chair that receives a user and typically two or more sets of wheels. Generally, the set of drive wheels are individually powered by motors and the secondary set of wheels are casters for stability. The motors can provide variable amounts of power to each of the wheels so that providing the same amounts of power to both wheels propels the wheelchair forward or backward. The wheelchair can be made to turn by applying more power to one wheel than the other. The exact manner in which a wheelchair is steered and powered can, of course, vary based on the implementation and different types of wheel configurations, including front-wheel drive; mid-wheel drive and rear-wheel drive are commonly available. The interaction of the control system and the wheels is similar for all of the possible implementations of wheel arrangements.
Generally, the steering mechanism includes a control apparatus. In one common implementation, the control apparatus is comprised of a joystick that is positioned on an armrest of the wheelchair such that the user can control both the operation and the driving of the wheels by manipulating the joystick in the direction of desired travel. When the user wishes to go straight forward or back, the user points the joystick straight forward or back which engages the wheels to travel in the indicated direction. For turning, the user directs the joystick in both a forward and left or right orientation to turn left or right going forward and backward in a left or right orientation to turn left or right going backward. Often, pointing the joystick in the absolute right or left orientation results in the wheelchair turning without forward or backward orientation. It will be appreciated that the exact operation of the control apparatus for the wheelchair can vary depending upon its implementation without departing from the spirit of the present invention.
One difficulty that occurs with wheelchairs having the above-described control apparatus is that the apparatus is susceptible to being manipulated in an undesired manner. Generally, the joystick is very exposed on the armrest as it allows easier access for the user. However, since the joystick is exposed, it can be inadvertently contacted by the user. For example, the user may be reaching for an article located adjacent the wheelchair and inadvertently contact the joystick resulted in sudden, unexpected movement of the wheelchair. The joystick being exposed also poses a threat to snag sleeves and other parts of clothing that causes the joystick to activate the control system of the wheelchair. This may result in the wheelchair suddenly striking objects or persons nearby or even causing the users body to run into objects or persons. In some circumstances, the sudden movement may cause the user to be ejected from the chair.
A further difficulty that occurs is that the exposed nature of the joystick may also result in bystanders inadvertently contacting the joystick and causing similar sudden unexpected movement of the wheelchair. As an example, friends and family of the wheelchair user often congregate about the wheelchair when talking to the user. When they engage in physical contact with the user, giving hugs, shaking hands and the like, individuals may inadvertently depress or move the joystick thereby causing the wheelchair to move in an undesired and unexpected direction. Hence, there is a need for a mechanism whereby inadvertent movement of the wheelchair is inhibited. To this end, there is a need for an interrupting device that inhibits activation of the wheelchair's motor when such activation is not desired by the user of the wheelchair.